The present invention relates to the art of molding. More specifically, the present invention relates to a stripper plate locking device for use with multiplate multiopening mold assemblies.
Stripper plate locking devices for use with two plate single opening mold assemblies are known. Two such devices are disclosed in U.S. Pat. No. 4,052,033 to Taylor and U.S. Pat. No. 4,372,738 to Black et al.
U.S. Pat. No. 4,052,033 discloses a resiliently loaded ejector pin return and detent means which comprises resiliently expandable means which operate to provide for the early return of ejector pins into a die cavity in flush relationship with an inner surface thereof to prevent a laterally movable slide mechanism from hitting the extended ejector pins.
The ejector pin return and detent means comprises a single generally tubular member having a plurality of resilient fingers surrounding a bore extending through the tubular member, the fingers being adapted to be spread apart by a return rod and the outer portions of the fingers being expandable by the return rod when forced therebetween such as to be of a greater external dimension than the bore of a sleeve fixed to one of the die cavity members and whereby, when the aforementioned fingers are in the bore of the sleeve, the internal space between the fingers is less than the cross-section of the return rod, such that the return rod applies force to the ends of the fingers and thus, forces them out of the bore of the sleeve at the beginning of the closing of one die relative to the other and thus, movement of the fingers out of the last mentioned bore by reason of the return rod causes an ejector pin carrying member to move in a direction to retract the ejector pins into their respective die cavity into flush relationship with an inner surface thereof and out of the way of laterally movable slide mechanism so as to prevent the slide mechanism from hitting the extended ejector pins. The specific structure of the ejector pin return and detent means comprises a generally circular array of resilient fingers which are formed generally of a circular cross section structure, and wherein slots separate the fingers such that they may be resiliently deflected outward relative to each other and relative to a bore extending through the tubular member with which the fingers are integral, the fingers being closer together at one end of the tubular member than the cross section of the complimental return rod and the bore of the tubular member near the opposite end thereof being large enough to allow the return rod to pass therethrough when it has forced the fingers apart by passing therebetween. The fingers are provided with generally frusto-conical cam surfaces diverging outwardly from the respective end of the bore and the return rod is provided with a generally conical or frusto-conical surface adapted to cooperate with the aforementioned cam surfaces on the ends of the fingers so as to force the fingers apart after the fingers have passed out of the bore at one end of the aforementioned sleeve.
U.S. Pat. No. 4,372,738 discloses a mechanism for locking together two mold parts movable between an open position spaced from each other and a closed position sealingly contacting each other, including an elongate tie rod which extends between the mold parts, is mounted on one of the mold parts, and has locking means thereon at a location spaced from the first mold part. A locking device provided on the other mold part can selectively engage the locking means on the tie rod for preventing lengthwise movement of the tie rod relative to the other mold part and includes a plurality of locking members which are disposed at angularly spaced locations about the axis of the tie rod and are supported for movement toward and away from the tie rod axis between retracted and locking positions. When the mold parts are in the closed position, the tie rod is received between the locking members and each locking member, when in the locking position, engages the locking means on the tie rod. An actuating mechanism is provided for effecting movement of he locking members between their retracted and locking positions, and a selectively actuable disable mechanism is provided for resisting movement of the locking members away from the locking position.
The locking device includes a collet sleeve which surrounds the tie rod axis and is fixed against movement relative to the second mold part in a direction parallel to the tie rod axis. The sleeve has a plurality of peripherally spaced slots therein which extend substantially axially from a first end thereof and define a plurality of axially extending arms which are resiliently flexible in directions substantially perpendicular to the tie rod axis, each of the locking members being provided at the free end of a respective one of the arms and on the side thereof facing the tie rod axis. When the mold parts are in the closed position, the tie rod is received within the collet sleeve. The collet sleeve has an outwardly facing surface at the first end thereof, and the disable mechanism includes a collar which surrounds the tie rod axis, is supported on the second mold part for movement parallel to the tie rod axis between first and second positions, and has an inwardly facing surface thereon which is engageable with the outwardly facing surface on the collet sleeve when the locking members are in the locking position and the collar is in the second position in order to prevent movement of the locking members away from the locking position.
The actuating mechanism includes an annular piston chamber which encircles the collet sleeve, an annular piston supported for reciprocal movement in the chamber and operatively coupled to the collar, and a mechanism for selectively supplying pressurized fluid to the piston chamber on opposite sides of the piston to effect reciprocal movement of the piston, which reciprocal movement in turn effects reciprocal movement of the collar between its first and second positions.
The above described prior art is not suitable for use with multiplate multiopening mold assemblies. Stripper plate locking devices for such are also known. Such devices are commercially available, for example, from Hasco.RTM. a German company under part numbers Z171/ and Z170/. The Z171/ part number comprises a housing and a base which are mounted onto the mold plate to be drawn. A latch bar is secured to the moving plate while a control bar is secured to the stationary plate. Accordingly, when the machine opens the mold, the mold plate opens from the stationary plate until a slanted portion of the control bar disengages a sliding lock. The moving plate can now be opened from the mold plate. The stroke of the mold plate is limited in this position. The length of the slanted portion corresponds to the minimum movement of the latch locking unit. The Z/170 part number comprises a latch housing and a base plate mounted onto the mold plate to be drawn. A latch bar is secured to the moving plate and a lock and release bar is secured to the stationary plate. A locking roller is pressed by the lock and release bar into a recess in the latch bar and makes a positive connection with the mold plate to be drawn. Accordingly, when the machine opens the mold the mold plate opens from the stationary plate. The inclination of the lock then releases the locking roller and the latch bar moves further opening the mold plate from the stationary plate. The mold plate is mechanically held in this position by the sliding lock.
Other latch locking devices are also available (e.g., D-M-E Jiffy Latch-Lok). While, these devices are designed for multiplate multiopening molds, they require an excessive amount of set up time. Accordingly, a need exists for an improved stripper plate locking device for use with multiplate multiopening mold assemblies.